Clarify that N remains reserved under Sv39/48/57

Svnapot overrides that.

1 files changed, 5 insertions, 8 deletions

diff --git a/src/supervisor.tex b/src/supervisor.tex
index f718ecc..e426beb 100644
--- a/src/supervisor.tex
+++ b/src/supervisor.tex
@@ -1812,13 +1812,10 @@ root page table is stored in the {\tt satp} register's PPN field.
 The PTE format for Sv39 is shown in Figure~\ref{sv39pte}.  Bits 9--0
 have the same meaning as for Sv32.
 
-The N bit indicates that the page represents a
-naturally-aligned power-of-two range of contiguous translations, as defined in
-the Svnapot extension in Chapter~\ref{svnapot}.
-
-Bits 62--54 are reserved
-for future standard use and must be zeroed by software for forward compatibility.
-If any of these bits are set, a page-fault exception is raised.
+Bit 63 is reserved for use by the Svnapot extension in
+Chapter~\ref{svnapot}.  Bits 62--54 are reserved for future standard use.  All
+of these bits must be zeroed by software for forward compatibility.  If any of
+these bits are set, a page-fault exception is raised.
 
 \begin{commentary}
 We reserved several PTE bits for a possible extension that improves
@@ -2124,7 +2121,7 @@ equals 8.
 \chapter{``Svnapot'' Standard Extension for NAPOT Translation Contiguity, Version 0.1}
 \label{svnapot}
 
-In Sv39, Sv48, and Sv57, when a PTE has N=1, the PTE represents a
+In Sv39, Sv48, and Sv57, when Svnapot is enabled and a PTE has N=1, the PTE represents a
 translation that is part of a range of contiguous virtual-to-physical
 translations with the same values for PTE bits 5--0.  Such ranges must be of a
 naturally aligned power-of-2 (NAPOT) granularity larger than the base page